Does cardiac arrest timing affect survival of patients?

The timing of cardiac arrest does not appear to influence the return of spontaneous circulation (ROSC) rate or 90-day survival, a Singapore study has shown.

“[O]ur study found no significant difference in immediate ROSC or 90-day survival [following] in-hospital cardiac arrest (IHCA) between cardiac arrests occurring during and after office hours,” the authors said.

“Among patients with ROSC, the duration of resuscitation was found to be significantly longer in patients who suffered a cardiac arrest after office hours as compared with those who had a cardiac arrest during office hours,” they added.

A retrospective cohort study was conducted to explore the characteristics of patients who sustained an IHCA, including the Cardiac Arrest Survival Post Resuscitation In-hospital (CASPRI) scores, and the impact of arrest time in 220 consecutive cardiac arrests occurring in a tertiary hospital.

Among patients with IHCA, the rates of ROSC were 75.4 percent during and 69.5 percent out of office hours (odds ratio [OR], 0.74, 95 percent confidence interval [CI], 0.39‒1.42). No substantially significant differences were noted between the CASPRI scores of both groups. The adjusted OR of ROSC post-IHCA out of vs during office hours was 0.78 (95 percent CI, 0.39‒1.53). [Singapore Med J 2026;67:104-108]

The 90-day survival rates were 25.7 percent for patients with IHCA out of office hours and 34.6 percent for those with IHCA during office hours (OR, 0.65, 95 percent CI, 0.32‒1.34). In adjusted analysis, the OR of 90-day survival was 0.66 (95 percent CI, 0.28‒1.59).

“There was no difference in the duration of resuscitation for patients who had no ROSC,” said the authors, adding that the “presence of a shockable rhythm was significantly associated with higher odds of 90-day survival post-ROSC.”

Resuscitation

Rapid initiation of high-quality and coordinated cardiopulmonary resuscitation, or CPR, by advanced cardiac life support-trained personnel contributes to survival in patients who had cardiac arrest. [Resuscitation 2015;94:106-113; Clin Med Res 2014;12:47-57; Anesthesiology 2019;130:414-422; Resuscitation 2018;129:76-81]

“There was also no difference in cardiac arrest team response times during and after office hours in our study, which was also likely contributory to the absence of difference in ROSC rates,” the authors said.

Furthermore, the cardiac arrest team consisting of a dedicated intensive care unit-trained nurse, respiratory therapist and registrar grade doctor, and rapid activation through a centralized call centre, stayed the same during and after office hours. This potentially contributed to sustained rates of immediate ROSC during and after office hours, according to the authors.

When comparing survival outcomes between groups, the presence of ventricular fibrillation appeared to increase the likelihood of 90-day survival.

This finding is consistent with current medical literature, as shockable rhythms tend to have a cardiac cause of arrest that may be reversed more easily and may indicate that the arrest was detected earlier, prior to deteriorating towards either pulseless electrical activity or asystole. [BMJ 2019;367:l6373; BMJ Qual Saf 2016;25:832-841]

“Further collaboration to develop multicentre studies that will determine the impact of various interventions on IHCA and improve care for these patients in the local context should be considered,” the authors said.